Embodiments described herein relate generally to door latches, and more particularly to latch operator connection apparatus for a mortise lock that is inserted in a mortise in the edge of a door.
A mortise lock includes a housing with, among other things, a hub rotatably disposed in the housing and operatively connected through linkages to a latch bolt. Rotating the hub in one direction effects linear retraction of the latch bolt. A latch operator such as a knob or a lever handle is provided for rotating the hub. A spindle, which is usually square in cross section, connects the latch operator and the hub. The hub defines a receptacle, also usually square, for nonrotatably receiving the spindle. When either handle is rotated or depressed, the hub rotates, which results in retraction of the latch bolt, allowing opening of the door. Two separate hubs may be provided in a mortise lock, where inside and outside latch operators independently operate each hub. The two hubs are coaxial, but are functionally separate from one another.
Some configurations of a spindle may include a unitary spindle that extends through the case and is secured at each end to the inside and outside latch operators, respectively. In this arrangement, the inside handle is permanently engaged with the hub and the outside handle. A second configuration consists of separate spindles for each of the latch operators. The separate spindles may be joined at their inner ends by an “all-thread” threaded rod such that the spindles are connected but may rotate relative to one another. This second configuration can be used with a single hub or two independent hubs. In the latter arrangement, the latch operators separately actuate the hub or hubs. Assembly and disassembly may require significant time and effort.